The present invention relates to a field emission display; and, more particularly, to a triode-type field emission device having a field emitter composed of emitter tips with the diameter of nanometers and a method for fabricating the same.
Generally, in a field emission display a strong electric field is applied to a cathode of a field emitter to emit electrons, wherein the electrons excite phosphor materials deposited on an anode. The field emission display includes upper and lower panels. The upper panel includes the anode and the lower panel includes the cathode (the field emitter).
The conventional field emitter is composed of a plurality of emitter tips and fabricated by a metal or a semiconductor material such as silicon. There has been a problem that the conventional field emitter fabricated by the semiconductor material additionally needs a complicated process, e.g., an aging process to ensure the uniformity of an electron emission. Furthermore, when the electrons are emitted for a long time, the semiconductor field emitter may cause the degradation of the emitter tips.
As the field emitter, nanotubes made up of carbon or boron nitride and nanowires made up of gallium nitride or silicon carbide may be employed in a conventional diode-type field emission device. Since the nanotubes and the nanowires form the geometric structure having great aspect ratio, respectively, the nanotubes and the nanowires may be employed as the emitter tips having the diameter of nanometers. To fabricate the conventional diode-type field emission device having the carbon nanotubes, a print process and a chemical vapor deposition process have been employed, wherein the print process mixes grown carbon nanotubes with silver paste and adheres the carbon nanotubes to a substrate and the chemical vapor deposition process vertically deposits the nanotubes on the substrate. However, it is difficult for the print and chemical vapor deposition processes to be used to fabricate the field emission display. Also, there has been a problem that the conventional diode-type field emission device needs a high voltage of several hundred volts to several thousand volts to emit the electric field.
It is, therefore, an object of the present invention to provide a triode-type field emission device having a field emitter composed of emitter tips with the diameter of nanometers that may operable in a low voltage.
It is another object of the present invention to provide a triode-type field emission devices that may increase the number of emitter tips per unit area.
It is further another object of the present invention to provide a field emission display including triode-type field emission devices that respectively have a field emitter composed of emitter tips with the diameter of nanometers.
It is furthermore another object of the present invention to provide a method for fabricating a triode-type field emission device having a field emitter composed of emitter tips with the diameter of nanometers that may simply implement the triode-type field emission device in an effective manner.
In accordance with one embodiment of the present invention, there is provided a triode-type field emission device, comprising: an insulating substrate; a cathode formed on the insulating substrate; a field emitter aligned on the cathode, wherein the field emitter includes a plurality of emitter tips and each emitter tip has the diameter of nanometers; an insulating layer formed around the field emitter for electrically isolating the field emitter; and a gate electrode formed on the insulating layer, wherein the gate electrode is closed to an upper portion of the field emitter.
In accordance with another embodiment of the present invention, there is provided a field emission display, comprising: a plurality of triode-type field emission devices; and a fluorescent material excited by electrons emitted from the triode-type field emission devices, wherein each triode-type field emission device includes: an insulating substrate; a cathode formed on the insulating substrate; a field emitter aligned on the cathode, wherein the field emitter includes a plurality of emitter tips and each emitter tip has the diameter of nanometers; an insulating layer positioned around the field emitter for electrically isolating the field emitter; and a gate electrode formed on the insulating layer, wherein the gate electrode is closed to an upper portion of the field emitter.
In accordance with further another embodiment of the present invention, there is provided a method for fabricating a triode-type field emission device, comprising the steps of: (a) forming a cathode on an insulating substrate; (b) patterning a metal layer on the cathode; (c) selectively growing a field emitter on the metal layer, wherein the field emitter includes a plurality of emitter tips and each emitter tip has the diameter of nanometers; (d) forming an insulating layer on the field emitter; (e) forming a conductive layer of a gate electrode on the insulating layer; (f) selectively removing the conductive layer of the gate electrode; and (g) exposing the field emitter by etching the insulating layer.
In accordance with furthermore another embodiment of the present invention, there is provided a method for fabricating a triode-type field emission device, comprising the steps of: forming a gate electrode on a first substrate; forming an insulating layer to open a predetermined portion of the insulating layer and to cover the gate electrode; forming a metal isolating layer on the insulating layer; depositing a seed metal layer of a field emitter on the first substrate, wherein the field emitter includes a plurality of emitter tips and each emitter tip has the diameter of nanometers; growing the field emitter on the metal layer; removing the metal isolation layer; providing a cathode positioned on a second substrate; depositing the cathode on the resulting structure; removing the first substrate and the seed metal layer; and selectively etching the insulating layer to expose the sidewalls of the gate electrode.